IRF (Kiruna, Sweden), IRAP (Toulouse, France), UCL/MSSL (London, UK), NASA/GSFC (USA), FMI (Helsinki, Finland), Inst Space Sci. (Bucharest, Romania), UNH (Durham, USA), OEAW (Graz, Austria), IRF (Uppsala, Sweden), UCB/SSL (Berkeley, USA), UCLA (Los Angeles, USA), U. Alberta (Edmonton, Canada), SwRI (San Antonio, USA), Inst Atmospheric Physics (Prague, Czech), IASB-BIRA (Brussels, Belgium)

NItrogen Ion TRacing Observatory (NIITRO):

a possible mission for next ESA's M-class call

M. Yamauchi, I. Dandouras, and NITRO proposal team

R28@GI2.3 (EGU2014-3822) Tuesday 2014-04-29

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Multi-disciplinary aspects of N+ and N2+

Origin of Life (ancient atmospheric composition) Amino acid formation depends on oxidation state of N (NH3 or N2 or NOx) = relative abundance of N, O, & H near surface

Planetary atmosphere (origin and evolution) N is missing on Mars (0.01% of Earth ~ Venus ~ Titan)

Magnetosphere (ion dynamics and circulation) N+/O+ changes with F10.7 & Kp (Akebono cold ion obs.)

Ionosphere (heating and ionization) N+/N2

+/O+ ratio @ topside ionosphere depends on solar activity

Plasma Physics (acceleration) Different V0 between M/q=14 and M/q=16 gives extra information

2But, no observation of N+/O+ ratio at 0.1-10 keV range

Present knowledge on N+/O+ ratio in space

(a) Dependence on geomagnetic activities is larger for N+ than O+ for both <50 eV (Yau et al., 1993) and > 30 keV (Hamilton et a., 1988).

(b) N+/O+ ratio varies from <0.1 (quiet time) to ≈ 1 (large storm). What we call O+ is eventually a mixture of N+ than O+.

(c) [CNO group]+ at <10 keV range is abundant in the magnetosphere.

(d) N/O ratio at Mars and C/O ratio at Moon are extremely low compared to the other planets.

(e) Isotope ratio (e.g., 15N/14N) is different between different planet/comet. But this requires M/∆M > 1000 spectroscopy, and outside the scope of present study. 3

(1) In-situ methodIon Mass Spectrometer: high M/∆M but low g-factorIon Mass Analyser: high g-factor but marginal M/∆MPhotoelectron: exact M but requires very high E/∆EWave (ΩO+ & ΩN+): M/∆M f/∆f (0.01 Hz accuracy @ L=3)

(2) Remote sensing (line-of-sight integration)Optical N+ line (91nm, 108nm) & N2

+ line (391nm, 428nm): must fight against contamination from topside ionosphereOptical NO+ line: low emission rate but yet might be useful for calibration purpose by estimating ionospheric contribution

Possible methods separating N+ O⇔ + and N2

+ NO⇔ + O⇔ 2+

⇒ must be above the ionosphere & outside the radiation belt

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We start with 6-7 Re x 2000 km orbit to avoid radiation belt first 1-2 year, and gradually decrease apogee to explorer “dangerous” region

Propose: 3-spacecraft mission (high inclination)

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M-class: 3 medium-sized s/c S-class: 1 small in-situ s/c

In-situ measurement (spin)* Mass spectrometer:* Ion mass analyzers (hot): (1) Magnet only (2) Magnet & TOF (3) Shutter TOF (4) MCP-MCP TOF (5) Traditional reflection TOF* Ion mass analyzers (energetic): * Ion mass analyzers (cold): * Magnetometer* Electron (simple or advanced)* Potential Control* Langmuir Probe* Wave (correlation to N/O ratio)* ENA (monitoring substorm)

Needed PayloadsRemote measurement (3-axis)* Optical (emission) (1) N+: 91 nm, 108 nm (2) N2

+: 391 nm, 428 nm (3) O+: 83 nm, 732/733 nm* Electron (simple or advanced)* Magnetometerr (∆f < 0.01 Hz)* Ionospheric monitor (sounder, optical)* ENA (1-10 keV): first time tailward monitoring of substorm injection

• Two in-situ spacecraft is for gradient observation.• Optical imager needs a scanner keep in-situ spacecraft within FOV.

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In-situ satellites (to be modified)

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Magnetic high-cleanness is required only for Mother A/C

Ion Instrument RequirementMass resolution: MO/(MO-MN) = 8 and MNO/(MNO-MN2) ≈ MO2/(MO2-MNO) = 16.

Energy resolution: (EO+-EN+)/EN+=15%, but stepping can be wider.

G-factor: G-factor N+ should be the same as for O+, i.e., G>10-4 cm2 str keV/keV without efficiency.

Time resolution: ∆t = few min is sufficient after integrating over several spins (and slow spin is ideal)

(1) Ion Mass spectrometer (fine N/O ratio): If N+/O+ = 1/100 is to be detected for Gaussian spread, we need M/∆M ≥ 200. Otherwise, low temporal resolution (5 min) is ok.

(2) Hot Ion Mass analyser 1 (changes of N/O ratio): If the data is calibrated, M/∆M ≥ 8 with ∆E/E ≤ 7% (ideally 4%) can do the job. Otherwise, wide FOV (separate and // directions) and without H+ is OK.

(3) Hot Ion Mass analyser 2: Narrow FOV with 2π (tophat) angular coverage and ∆E/E ≤ 15%. Otherwise, M/∆M ≥ 4 (H+, He++, He+, CNO+, molecule+) is OK

(4) It is nice to have simple ion energy spectrometer (without mass) for ∆E/E< 4% and high- & temporal resolution

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Science Question What &where to measure? requirement

N+ escape history vs O+ or H+

N+, O+ and H+ observation @ escape route and destinations @ different solar & magnetospheric conditions.

#1, ∆t~1mingradient+ imaging

Ion filling route to the destination

same as above. same as above.

Ionospheric energy re-distribution to N & O

N+, O+, H+, J//, and e- at different solar conditions.

#1, keV e-, J//, eV ions

Ion energization mechanisms

energy difference among N+, O+ and H+ at different altitude, wave and field

#1, ∆t<1mingradient, cyclotron i

Relation to substorm injection

correlation to ENA observation #1, ∆t~1min

#1: N+-O+ separation (narrow mass range) and H+-He+-O+ separation (wide mass range) at and // directions with ∆E/E ≤ 7% ((EO+-EN+)/EN+=15%) but E-stepping an be wider

Other sciences

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(1) We try first M-class (AO: 2014), and then S-class (2015/2016) if we fail M-class. The M-class is "comprehensive understanding of distribution using 2-point in-situ plus imaging" with full 3-spacecraft while S-class is "first core-spacecraft is used as pioneer of N+ search" with "core-spacecraft" only if M-class failed.

(2) We seek also NASA as possible partner or its own mission (in that case the European instrument should be co-I level).

(3) Launch is targeted for next solar maximum (before 2022). This gives extra opportunity that makes ongoing Van-Allen Probes and ERG to be extended for stereo observations.

(4) We welcome astrobiology team

(5) We welcome optical team

Strategy / Action items

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Nitrogen (N/O ratio) Mystery

MarsVenus Earthrich in N

N < 0.01% of Earth/Venus

N/O ratio at Mars << at the Earth, Venus, Titan

Action Items on payload (New feedback from EGU 2014)

It might be a good idea to include ionospheric monitoring such as sounder or optical instrument (N2

+/N2 ratio tells energization of topside ionosphere). The ion escape should directly be related to the seed population, i.e., upper ionospheric condition. (But including sounder makes mission larger than M-class?)

It might be a good idea to include soil N2-N2O-NO-NO2 ratio remote sensing to correlate the change of oxidation state of N and and escape of N+ or N2

+. The remote sensing satellite already exists. (Quetion is how to compare?)

We have to define "purely supporting" instruments that should be paid as a part of spacecraft (not as SI), such as the Active Potential Control. How about Langmuir Probe?

It might be a good idea to measure E-field for accurate measurement of particles (but aren't LP and APC enough?)

END

North

South

In-situ obs.

Imaging

All types of ion mass analysers: (1) Magnet (2) Shutter TOF (3) Reflection TOF (various types)

Supporting instruments

ENA of 1-10 keV (substorm injection)

Optical (emission) (1) N+: 91nm, 108nm (2) N2

+: 391 nm, 428nm (3) NO+:

Skip Mission orbit and Payload

* Clarify the need of instrument for science (going)

* Define spec (observation limit) vs science requirement

* Define resolution (integration time for one direction)

* How many different ion instruments are needed?

* We need more European instruments

* NASA relation (how to include US-lead instruments?)

* Radiation dose (homework for each SI)

* How much EMC cleanness requirement do we ask?

Other Action Items